Permanent thirst: what this symptom can talk about

The constant thirst is when a person wants to drink more often than usual, and this desire arises regardless of physical activity, temperature indices of the air, salinity of food and other external factors.

In itself, usual thirst is a normal reaction of the body to the violation of water-salt homeostasis, because water plays the most important life-supporting role and participates in almost all metabolic processes. But if there is a constant unquenchable thirst (polydipsia), then it is necessary to understand the causes of this abnormal condition.

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Causes of constant thirst

Domestic medicine considers the physiological norm of water consumption (not in the summer heat) to be approximately 40 ml per kilogram of body weight. Often, the optimal volume of drink is 1.2-1.5 liters per day. According to the recommendations of the Institute of Medicine (USA), men need almost 3.7 liters of water per day (20-25% - from food, including drinks), women - less per liter. WHO has developed other standards: for men - 2.9 liters, for women - 2.2 liters. In general, as of today, there is no common opinion, as you can see, has not been worked out.

The signal about the need to replenish water reserves in the body comes from the so-called drinking center of the central nervous system, which includes the nucleus of the posterior lobe of the hypothalamus, the limbic region of the cerebral hemispheres and certain areas of their cortex. And most often the causes of constant thirst lie in the failures of the work of this center.

Due to hypothalamic receptors, the drinking center perceives all fluctuations in the amount, osmotic pressure and level of Na + in the fluid of all body structures and responds to them. These reactions are reflex, and neurohormones of the renin-angiotensin-aldosterone system are involved in them: vasopressin (synthesized by the hypothalamus), angiotensin (formed in the blood), renin (produced by the kidneys) and hormone of the adrenal cortex aldosterone. This process is affected by the hormones of the thyroid gland, as well as insulin produced by the pancreas.

It should be borne in mind that a constant increased fluid intake is not classified as a disease: in medicine, permanent thirst is considered as a symptom of the disease.

In many cases, the causes of constant thirst are associated with such diseases and pathological processes as: chronic diarrhea; frequent vomiting; fever; head trauma; infectious intoxication; decrease in blood volume (with internal bleeding or systemic capillary leak syndrome); diabetes mellitus (hyperglycemia); non-sugar (insulin-independent) diabetes of a neurogenic, nephrogenic or dipsoogenic etiology.

So, the typical thirst and frequent urination (polyuria) characteristic for diabetes insipidus can be related:

• with different in the etiology of hypothalamic damage (including tumors), which lead to a disruption in the synthesis of the water-electrolyte regulating metabolism of the antidiuretic hormone vasopressin;
• with a decrease in osmolality (the concentration of anions, cations and non-electrolytes) of blood plasma;

With a low sensitivity (or its complete absence) of recurrent renal tubules to vasopressin.

Pathological thirst is also included in the complex of clinical symptoms:

• chronic renal failure (nephropathy, pyelonephritis, amyloidosis, etc.);
• thyrotoxicosis (hyperparathyroidism);
• primary hyperaldosteronism or Conn's syndrome (caused by hyperplasia of the adrenal cortex and increased production of aldosterone, leads to deficiency of potassium ions - hypokalemia);
• hypohydration in edema;
• hyperhidrosis (excessive sweating);
• hypercalcemia;
• hyponatremia;
• syndrome of hypercorticism (Itenko-Cushing syndrome);
• adrenal adrenal and adrenocortical cancers.

There is a constant unquenchable thirst and polyuria in congenital genetic pathologies: acromegaly (which occurs when the functions of the anterior lobe of the pituitary gland are disturbed), acetuloplasminemia, Bartter's syndrome (reduced absorption of chlorides and sodium by the kidneys), cystinosis, Parkhon syndrome, Fanconi syndrome, sickle cell anemia.

Constant dry mouth and thirst accompany the reception of certain drugs, in particular, all diuretics, most antibiotics, as well as lithium-containing antipsychotic (neuroleptic) drugs.

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Constant thirst during pregnancy

European doctors claim that during pregnancy during the day, women need to drink more - almost 300 ml, but the total amount of consumed liquid should not exceed two liters.

But there is a constant thirst during pregnancy (especially at the term of 27-36 weeks), which is explained by the increased synthesis of the protein of angiotensinogen in the liver and, accordingly, an increase in its intake into the bloodstream. In gestation, this is due to an increase in the production of corticosteroids and estrogen, a change in the mineral balance.

In addition, as intrauterine development of the fetus, there is a need to accelerate the glomerular (glomerular) filtration of the kidneys working during pregnancy with increased stress. And contributes to this high level of angiotensin, which causes increased thirst in expectant mothers.

Biomechanics of homeostatic processes during child bearing is due to the fact that angiotensin in increased amounts promotes the growth of the synthesis of the already mentioned aldosterone - the hormone of the adrenal cortex, which leads to loss of blood plasma by potassium ions and retention of excess sodium ions.

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Constant thirst in the child

Let's begin, again, with the norms of water consumption. Recommendations of the World Health Organization regarding the drinking regime in childhood are based on the body weight of the child: a three-month-old baby weighing up to 5 kg per day needs at least 700-800 ml of liquid,

A one-year-old child weighing 10 kg - 1 liter of water. Breast milk is included in this standard, since it contains more than 86% of water.

According to the recommendations of American pediatricians, a child from one to three years of age normally consumes about 1.3 liters of liquid per day, including about 350 ml of milk, as well as water, soups, fresh juices and other beverages. From 4 to 8 years you need 1.7 liters a day.

At the age of 9-13 years, boys need 2.4 liters of fluid per day (European experts call another figure - 1.6 liters). And at the age of 14-18 years teenagers and young men need 1.9 liters of fluid per day, girls and girls - at least 1.6 liters (American standard - 2.7 liters and 2.4 liters, respectively).

If there is a constant thirst in the child, then its causes can be associated with one or more of the above factors. To clarify the specific etiology of the child should be examined: perhaps the child is simply very mobile, and this increases the flow of water to maintain normal water-salt balance. But pathology is not excluded, either as an exchange, or as a neurohumoral one.

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Diagnosis of a constant thirst

The correct diagnosis of constant thirst, that is, the identification of specific causes of its occurrence, involves the collection of a detailed anamnesis, in which the doctor must take into account all the features of the patient's health status - from the number of urination during the day to the characteristics of his usual diet.

Patients must pass:

• blood test for glucose in the plasma (including fasting);
• blood test for the level, potassium, calcium and sodium (osmotic concentration);
• blood chemistry;
• general urine analysis;
• urine analysis for relative density.

Based on the results of the tests, the patient may need to consult an endocrinologist, hematologist, nephrologist, as well as CT or MRI of the brain, kidneys, adrenals.

How to satisfy a constant thirst?

To know how to quench constant thirst, you need to determine the optimum amount of water consumed to maintain a fluid balance. Given that the water-salt metabolism can have individual characteristics, the need for replenishment of the fluid in the body can vary significantly among different people and depends on their gender and age, the state of the psyche and the level of physical activity, the climatic conditions of the place of residence.

Remember that no sweetened carbonated drinks, as well as beer, quench your thirst. Also, doctors do not recommend drinking mineral water containing various salts. Strongly cooled water also does not help, since the body best absorbs liquids at a temperature of + 22-25 ° C.

What can be the prevention of constant thirst? In refusing to eat spicy, salty and fatty foods. It is necessary to eat more products, rich in water - vegetables and fruits. "Water-supplying" dieticians consider cucumbers, apples, oranges, melons, watermelons. Very good relieve the feeling of constant thirst unsweetened green tea at room temperature, a decoction of apple peel, water with the addition of fresh lemon juice or grapefruit. You can also rinse your mouth with cool water.